The subject matter disclosed herein relates to a multi-degree of freedom transducer for converting manually applied forces and/or torques into electrical signals, and more particularly, to a six degrees of freedom transducer for a medical tableside user interface enabling motion-control of mechanical and/or virtual components.
In medical applications it is often necessary to position a patient with respect to an external x-ray or radiotherapy beam. In the field of radiotherapy and X-ray imaging the irradiation of beams requires very high precision, it is therefore of prime importance to position the patient correctly with respect to the radiation. In radiotherapy and X-ray imaging, the patient is generally placed on a table and then the table and/or the X-ray device is positioned using electromechanical equipment.
In recent years, there have been proposed joystick-like or button-based manipulators to perform mechanical positioning in medical applications. In such proposed systems, one of the common problems is that a number of joysticks or buttons are necessary to enable six degrees of freedom positioning, making the positioning difficult. An operator has to observe the motions of the controlled object, i.e. a visual feedback is necessary which is highly disadvantageous in medical applications where often quick actions are necessary.
Furthermore, the joystick-like controllers involve complex moving parts, difficult replacement of the transducer elements, and some systems do not provide six degrees of freedom sensing. A further requirement for such controllers is that they should enable their manipulation also if covered with a replaceable aseptic foil for a longer period without the risk of damaging the foil. This is not really possible with moveable controllers, e.g. joysticks. Space saving is also essential around the table to allow the doctors to do their job. In some medical applications, the operations are to be carried out in a dark environment, especially when surgical actions are followed on screens. The known controllers do not allow their use in such situations, as they can not be properly actuated if they are not or are hardly visually locatable.
U.S. Pat. No. 6,459,092 B2 discloses a six degrees of freedom motion measuring apparatus using a multidirectional reflector and a swing arm type optical system. This optical measurement is not suitable for the above intended purposes.
U.S. Pat. No. 4,369,663 discloses a six degrees of freedom transducer for a manipulator. The transducer contains moving parts and is based on capacitive displacement measurement. Moving, parts have the drawbacks above and are more sensitive to dust and contamination.
Thus, there is a need for a solution allowing an improvement over existing methods and devices. There is a need to provide a multi-degree of freedom transducer, especially for medical purposes, which eliminates the drawbacks and deficiencies of the prior art techniques. There is a particular need for a transducer having a relatively small size, not containing moving parts and enabling its application in sterile and dark workplaces. There is also a need for a transducer that enables that the controlled object moves according to a wrist motion of an operator through strain measurement.